The invention relates to billing a subscriber in a telecommunication system, and particularly to billing a subscriber in a multi-provider environment in a mobile communication system. The mobile communication system generally refers to any telecommunication system which enables wireless communication when users move in the service area of the system. A typical mobile communication system is a public land mobile network PLMN.
Telecommunication systems are increasingly changing over to a multi-provider environment wherein access is provided by an access operator, telephony by a telephony operator and actual services by one or more service providers. This is the case particularly in systems called third generation mobile communication systems, such as a universal mobile communications system UMTS. In the UMTS, for example, the actual mobile communication network can operate as an access network providing the user with wireless access to external networks, such as Internet protocol IP networks and the services thereof, such as IP telephony IPT. One access network usually provides access to several external networks, which can be of a similar type. There can be several telephony operators, for example, which provide the IPT service. When the access operator is not the telephony operator, both operators typically collect their billing information in their own networks and bill the subscriber separately. A service provider itself does not maintain the network but purchases a necessary network service from the network operator, which collects billing information on behalf of the service provider as if it were the network operator's own billing information. The network operator also bills the subscriber on behalf of the service provider. In other words, if the service provider purchases the network service from the access operator, the access operator is responsible for collecting the billing information on the service and for billing according to an agreed tariff. The telephony operator operates in a similar manner if the service provider should purchase the network service from the telephony operator.
A service of the mobile communication systems becoming increasingly popular is a prepaid subscription. The prepaid subscription involves no billing in arrears but the account of the prepaid subscription is charged in real time during calls. The prepaid subscription can usually be used for chargeable calls until the credits in the subscription's account run out, in other words until the prepaid amount has been exhausted. Usually, the subscriber to the subscription, or someone else, can deposit more money in the subscription's account.
The problem is, however, how to implement a prepaid subscription which requires real-time billing during a call in a system comprising an access operator and a telephony operator, which both collect their own billing information and do not know each other's tariffs. For an end user, it is inconvenient if he or she is compelled to have at least two separate prepaid subscriptions, one being a subscription to the access operator and the other to the telephony operator. The same problem also arises in connection with a service similar to the prepaid subscription wherein the maximum amount of a bill, i.e. the maximum sum of money that a bill is allowed to be during a billing period, has been determined for a subscription to be billed in arrears.
It would also be more convenient for subscribers billed “normally” in arrears to receive a single combined bill instead of separate bills sent by the operators.